As a result of advancements in computer vision and wireless technology, Unmanned Aerial Systems (UAS) were typically used in special applications such as security works. But, with the availability of mini-unmanned aerial vehicles (UAV) and micro-UAVs in the market now, which are cheaper yet robust, UASs are being used in civilian applications which involve transmission of telemetry and multimedia data to the Ground Control Station (GCS).
The use of Unmanned Aerial Systems (UAS) for sensing applications is an upcoming technology. These applications involve remote sensing typically in outdoor areas. Most of these applications involve surveillance for monitoring of vast infrastructures that at times also run through harsh and uninhabitable terrains. Besides flight regulation, wireless communication is an important aspect of a UAS. It is essential to communicate between a UAS and a GCS wirelessly as telemetry information (navigation, control and guidance) and at times, sensor data is required to be transmitted to a ground based mission control center in near real-time. Traditional UASs take care of such communication by using proprietary communication systems. The available technology options are limited in the case of long range communications. It is difficult to construct multiple radio signal transmission towers inside harsh and uninhabitable terrains. Hence for communication between a transceiver on-board a UAS and a radio transceiver, the transceiver is almost always installed at the boundary of a habited place. The ground based transceiver may be part of Ground Control Station, or may have to relay the communication further to GCS. However, for such a topology or setup, it is difficult to have radio signal coverage deep inside such terrains, due to phenomena of diffraction, absorption, polarization and scattering, which result in (Rayleigh) signal fading. Additionally, it is difficult to plan a flight path that can factor maximal coverage availability in remote and non-urban places.
Moreover, for surveillance, especially in case of emergency breakdown of some infrastructural system, it is important to have connectivity for as long time as possible, during an operational flight of a UAS. This is to allow the sensed data to be sent to GCS in real time. Practical UAS applications do not have on-board sensor signal processing facility since that will curtail the flight duration. Also, even if the UAV is flight autonomous, for a secondary control mechanism in the case of UAS failure, real-time connectivity for telemetry is still needed. The operational flight using a mini-UAV typically lasts for an hour and covers tens of kilometers inside any region.
Thus, it is evident that aforementioned current methods of connectivity typically involving direct RF line-of-sight communication between a GCS and a UAS are limited in terms of distance/time till which they can ensure connectivity. Hence, there is a need for a system that provides connectivity between a UAV and a GCS for maximum period during the UAV flight.